Why do some handles need heavy sprung locks & latches
Some of the handles in our ranges are un-sprung - this means they have no attached spring to return the handle into the horizontal position. 
You will need to ensure that the locks and latches you have to work with the handles have a heavy spring in them so this will then ensure that the handles are bought back to the horizontal position.
If your handles do not return properly or you find they droop then your lock or latch does not have the correct springing required.
You can purchase some coil springs item: 8000060 / 8000061 which may help with the return springing rather than replacing your lock or latch.